PowerLogic T300 - Issue when reading analog data from PowerLogic P3

John_Archer1 · ‎2024-11-22

The analog value I am reading has a minus sign (-) and an incomplete value. What settings am I making a mistake in? Has anyone had this problem? I am

Read setting t300IEC101 settingP3 Line voltage Measured valueP3 scale settingT300 Reading voltage view webserver

Mathieu_Lansoy · ‎2024-12-12

Hello,

In standard, MMEB format should transmit signed 16-bit values (so from -32768 to + 32767).

These measurements will be managed in this format by PowerLogic T300 if they have been declared as MMEB.

Apparently, the P3 uses unsigned 16-bit values (from 0 to 65536) and does not scale down the values.

1. If the value is less than 32767, no issue.

2. If the value is higher than 32767, the most significant bit of the 16-bit format will be set and treated as a negative sign by T300. This explains the values shown on T300 WebApp (see example below).

Ex: 33933 V -> 0x848D -> -31603 (signed 16-bit value).

If no scaling system can be found on the P3, we can use PowerLogic T300 logic formulas to correct the value, by adding 65535 to the negative values (see below):

Another idea: use the "normalized" (MMEA) format proposed by P3 (but I don't know how the conversion can be done in this case - maybe using the corresponding "Max" setting that can be seen on the "IEC 60870-5-101: AI" page.

regards,

Mathieu.

See Answer In Context

sathishkumar_ramakrishnan · ‎2024-12-02

Hello John Archer,

In MMEB the value stored in coreDb is converted in a 16-bit entire signed value. So once it exceeds the 16 bit range,it throws the negative value. Hence you need to change the phase voltage AB, BC and CA data type as MMEC which is 32 bit floating value has wide range.

If you want to use the data type as MMEB only, then you need to scale down the value to 16 bit range.

Regards,

Sathish

John_Archer1 · ‎2024-12-04

@sathishkumar_ramakrishnan Thanks for the reply. The Easergy Relay I am using only reads MMEB values. How do I change from 32-bit to 16-bit value? Also, the measurement format is not normalized and does not transmit analog information at all.

sathishkumar_ramakrishnan · ‎2024-12-11

Hello John,

I have tested this MMEB values of the PowerLogic P3 relay with the TMW 101master [ Simulator tool], thus taking PowerLogic T300 out of the equation: the phase voltage values are displayed negatively (see attached screen shot of the same).

The Easergy Pro software will show the correct value, since it is not the standard protocol implementation tool. As I mentioned earlier MMEB datatype is a 16-bit value only: hence its showing negative values once it crosses the range.

From P3 relay, using a scaling factor is needed to provide the 16-bit data to T300 or to any IEC101 master device integration for correct data representation. However, I have not been able to find information regarding the scaling factor for P3 relay.